First, the filly Eight Belles falls awkwardly after finishing second at the Kentucky Derby, becoming one of some 5,000 horses that have died in the US since 2003.

Then Big Brown, a beefy 3-year-old bay colt that dominated the Preakness and the Derby, shockingly peters out on the final stretch at the Belmont Stakes – the first Triple Crown contender to ever finish last.

And now this week Congress begins hearings on the ethics of horse racing, auguring the end of a steroid-boosted era of superhero colts and phenom fillies – a three-decade span that has been unable to produce a Triple Crown winner.

Hooves down, it's been a tough year for the $40 billion US horse racing industry. As the world watched the Eight Belles tragedy on the track last month, horse racing overall saw attendance fizzle and wagering flatline – signs that one of the world's oldest sports is wrestling with some of modern society's toughest questions about the effects of greed on animal husbandry.

"When you talk about the Kentucky Derby, Belmont, Preakness, the whole country focuses on those, they attract stars from Hollywood, and it's all pretty romantic and wonderful," says US Rep. Ed Whitfield (R) of Kentucky, who holds hearings Thursday. "But in everyday racing, there are horses going down, and then the horses unable to fulfill their promise going to slaughter. The greed has trumped the concern for the horse, it's trumped the safety of the jockeys, and it's trumped the integrity of the sport."

In 1980, former US Sen. Charles "Mac" Mathias, Jr., a Maryland Republican, warned breeders to reform or face a congressional cavalry storming their barns. At stake this week is whether Congress will make good on that threat as the industry has grown rich on US-sanctioned simulcast betting while, critics say, overbreeding and overmedicating horses for speed at the expense of soundness, with some 37 percent of race-bred horses going to the slaughterhouse each year.

Congress will look at the lack of record-keeping about some facets of the sport, race day and maintenance doping, natural versus synthetic tracks, and the sport's special gambling status, where Congress sanctions and regulates simulcast racing. The main challenge will be to create some kind of national framework to oversee fiefdoms that range from Saudi sheikh owners to small bluegrass farms – in other words, opening the barn doors to the light, says Rep. Whitfield.

Changing societal views toward animals, especially those used for human enjoyment, has played a dramatic role both in racing's recent malaise and the decision by Congress to hold hearings. Fatal big-race breakdowns such as Eight Belles and Barbaro in 2006 only galvanized critics.

"I think it's kind of like dogfighting, cockfighting, and bullfighting in Spain, where different parts of Spain are starting to sit back and say, 'This is really cruel,'" says Laura Allen, executive director of the Animal Law Coalition in Kanab, Utah. "Just because we've been doing it a long time doesn't make it right."

The introduction of off-track betting in many states in the '90s meant grandstands started emptying out, but annual wagering increased from $9 billion to $15 billion. The use of medications, including anabolic steroids, is still legal in 28 of 38 racing jurisdictions, including the three states of the Triple Crown.

But doping came into focus this year as Big Brown's trainer, Rick Dutrow, Jr., who had been cited for doping violations in the past, stopped Big Brown's steroid regimen before the Belmont – only intensifying questions about its effects after the horse lost so dramatically a race he was widely favored to clinch.

For their part, racing proponents say racehorses face no greater threats than a kid's pony. With 1.9 fatal breakdowns per 1,000 starts, horse racing is relatively safe, they say, and injuries are comparable to barnyard accidents that claim thousands of horses every year.

Compared with other eras, today's horses run fewer races and many stables are staffed 24/7 with on-site trainers and veterinarians to address every limp and sniffle. What's more, steroids are often used for medical reasons. The drug given to Big Brown on the 15th of every month was geared to stimulate appetite, not improve performance directly, experts say.

"Let's not forget that the federal government maintains horse herds of 37,000, 38,000 horses on feral land in the West," says Tim Capps, a horse industry expert at the University of Louisville in Kentucky. "There are more horses many times over in their care killed every year in accidents, stepping in holes, bitten by snakes, being struck by lighting than ones who get put down as a result of an injury in a race."

But critics say that breeding bigger and faster horses – all in a very compressed time frame on the evolutionary scale – may have created more unsound horses. Adding powerful steroids to their health regimen is in itself an abdication of responsibility to the animals, argues champion breeder Arthur Hancock of Paris, Ky, who will testify this week.

"We're talking about living, breathing athletes here that are drugged to the hilt, and that's not right," says Mr. Hancock.

The question is whether the industry can change by itself. In many ways, it already is, contends Mr. Capps.

The introduction of 10 synthetic race tracks in the US has reduced the number of race day injuries, but these are expensive and not fully vetted. A national drawdown on the use of steroids is likely by the end of the year, even without congressional action. Jockey, breeder, and owner groups are looking at issues involving shoeing, track surfaces, and a better injury reporting system.

Because of such efforts, Kentucky state senator Damon Thayer this week called the hearings "objectionable" and said medication regulation should be handled by the states, not the federal government.

"You're seeing an industry literally changing substantially on the fly, and nobody's got a real good road map of where all this is going," says Capps. "We're in the middle of what is a political and philosophical entanglement that's very difficult to sort through."

But while Saudi sheikhs and gabardine-suited Kentucky gentry are the public face of horse racing, people sometimes forget that the sport ultimately involves people with a genuine love of horses, says Wendy Davis, associate director of the Race Track Industry Program at the University of Arizona in Tucson.

"We adore these animals and we do anything we can to make them safe," says Ms. Davis.

Yet this past racing season sounded a somber bugle call to a tumultuous season for a sport that may have gone beyond its ability to make ethical decisions on behalf of its steeds.

"Enough is enough," says Hancock, the Kentucky breeder. "It's time to abolish this stuff, run on natural ability, and have it all be aboveboard. If we do that, we've got a good future. If we don't, we'll continue to decline."